Islamic Inheritance (Faraid): How It Works, and a Calculator for the Common Cases

What is Faraid?

Faraid (from the Arabic root meaning "obligatory" or "fixed") is the body of Islamic law that governs how a deceased Muslim's estate is divided among surviving relatives. Unlike a system where a person can leave their entire estate to whoever they choose, Faraid assigns specific, largely fixed shares to a defined list of relatives, primarily the spouse, children, and parents, with other relatives inheriting in specific circumstances.

The core idea is that these shares are not left to individual discretion. A Muslim can still write a will (wasiyyah) for up to one third of the estate to benefit people who are not already fixed-share heirs, such as a friend, a charity, or a more distant relative, but the remaining estate (and, in most traditional views, the full estate if no such will exists) passes according to the fixed Faraid shares.

The Quranic basis

The traditional textual basis for Faraid comes primarily from the Quran, Surah An-Nisa, verses 11 and 12, which set out specific shares for spouses, children, and parents, and verse 176 of the same surah, which addresses the share of siblings when someone dies without children or parents. These verses are the reason Faraid is treated as a matter of fixed obligation rather than ordinary family custom or personal preference.

The detailed application of these verses, including how to handle every possible combination of surviving relatives, was worked out over centuries by Islamic jurists and is recorded in substantial detail across the different schools of Islamic law. That detail is what this page summarizes, and it is also why the subject supports entire specialized textbooks rather than a single short formula.

Who can be an heir

Islamic inheritance law generally recognizes two broad categories of heirs:

• Fixed-share heirs (Quranic sharers, ashab al-furud): relatives assigned a specific fraction of the estate by name, such as 1/8, 1/6, 1/4, 1/3, 1/2, or 2/3. This group includes the spouse, parents, and, in certain circumstances, daughters and siblings.
• Residuary heirs (asabah): relatives who inherit whatever remains after the fixed-share heirs take their portions. Sons are the clearest example: a son does not have a fixed fraction written down, he inherits the leftover residue, and he shares it with any surviving daughters in a 2:1 ratio.

Who actually inherits, and how much, depends entirely on who else survives. A father's position changes completely depending on whether the deceased left children. A sibling's position changes completely depending on whether the deceased left a father or children at all. This interdependence is the single most important thing to understand about Faraid: there is no universal percentage for "the wife's share" or "the son's share" in the abstract, only shares for a given combination of survivors.

Fixed-share heirs and their shares

The table below summarizes the most commonly taught fixed shares for the primary heirs covered by this site's calculator. It does not include every possible heir (grandparents and grandchildren, for example, have their own rules not covered here).

Notice how often a share depends on "if children" or "if no son." That conditional structure repeats throughout Faraid and is the main reason a simple lookup table cannot replace an actual calculation for a specific family.

Residuary heirs and the son-daughter ratio

When a son survives, he and any surviving daughters become residuary heirs together: after the fixed-share heirs (such as a surviving spouse, mother, or father) take their portions, the remainder is split so that each son receives twice the amount of each daughter. This is often summarized as a 2:1 ratio, and it is frequently the most misunderstood part of Faraid, because it is sometimes described, inaccurately, as "sons get everything" or "daughters get nothing." In the actual framework, daughters inherit alongside sons; they simply inherit at half the per-person rate of a son when both are classified as residuary heirs together.

A similar 2:1 relationship applies between full brothers and full sisters when they inherit as residuary heirs in a scenario with no children and no surviving father.

The father, when there are no surviving children at all, also functions as a residuary heir: he takes whatever is left after any surviving spouse or mother receives a fixed share, which can mean he receives the entire estate if no spouse or mother survives, or a reduced amount if they do.

Why the math gets complex

Three features of the system push real cases beyond a simple fraction lookup:

• Awl (proportional reduction): in some survivor combinations, the fixed shares that apply add up to more than the whole estate. When that happens, every fixed share is scaled down by the same proportion so the total equals exactly 100 percent. This procedure is agreed upon across the Sunni schools and is applied automatically by the calculator below when it is triggered.
• Radd (return) for leftover residue: in some combinations, the fixed shares add up to less than the whole estate and there is no son, father, or (in some scenarios) brother present to absorb the difference as a residuary heir. Whether and how that leftover is returned to the remaining heirs is a point where schools of thought and individual scholars have genuinely differed historically. Rather than silently pick one answer, the calculator on this page flags this situation explicitly when it comes up.
• Grandchildren, grandparents, and extended relatives: the full Faraid framework also covers son's children, daughter's children, grandparents, uncles, aunts, and more distant agnates, each with their own rules for when they inherit and how much. This page and its calculator deliberately cover only the most common, direct-family scenarios. Estates involving more distant relatives need a scholar familiar with the complete framework.

Sunni, Shia, and the schools of thought

The core fixed shares for spouse, children, and parents described above are broadly shared across Sunni Islam's four major schools, Hanafi, Shafi'i, Maliki, and Hanbali, for the straightforward cases this page covers. The schools do differ on a number of more specific questions, including exactly which relatives count as residuary heirs in less common combinations, how certain radd scenarios are resolved, and treatment of some extended family members.

Shia Islamic law, most commonly represented by the Jafari school, uses a structurally different approach to classifying heirs into priority classes, which can produce different outcomes than the Sunni framework in some scenarios, particularly those involving siblings, grandparents, or more distant relatives, even though it draws on the same Quranic verses as its starting point.

Because of these differences, this page and its calculator describe the framework most widely taught in Sunni contexts for common, direct-family scenarios. A family that identifies with a particular school, or with Shia jurisprudence specifically, should confirm details with a scholar versed in that school, especially for anything beyond the simple cases shown here.

Faraid calculator: common survivor cases

This calculator applies the fixed shares and residuary rules described above to the survivors you enter. It is built for the common, direct-family scenarios: a surviving spouse, sons and daughters, parents, and full siblings. It is not built to resolve every scholarly difference or every possible combination of extended family, and it says so explicitly in its notes whenever a scenario goes beyond what it can resolve on its own.

Worked examples

Working through a couple of examples by hand makes the logic easier to follow.

Example 1: spouse and one son only

A man dies leaving a wife and one son, with no other heirs. Since there are children, the wife's fixed share is 1/8. There is no daughter, so the son is the sole residuary heir and takes everything left over: 1 minus 1/8, which is 7/8. Result: wife 1/8, son 7/8.

Example 2: spouse and both parents, no children or siblings

A man dies leaving a wife, his father, and his mother, with no children and no siblings. The wife's fixed share with no children is 1/4. This specific combination, a spouse plus both parents with nothing else, is the classical case where the mother's share is commonly taught as one third of the remainder after the spouse's share rather than one third of the whole estate, specifically so the father's share stays double the mother's. The remainder after the wife's 1/4 is 3/4. One third of that remainder is 1/4, which is the mother's share. The father, as the residuary heir, takes what is left: 3/4 minus 1/4, which is 1/2. Result: wife 1/4, mother 1/4, father 1/2.

Both examples match what the calculator above produces for the same inputs. For scenarios involving daughters without a son, or siblings, the shares interact differently, which is exactly why the calculator exists rather than a single static table.

Islamic shares versus civil inheritance law

In most Western countries, a person's estate is distributed according to that country's own inheritance or probate law, not automatically according to Faraid. A will written under, say, U.S. or U.K. law is legally enforced according to that country's rules on wills, forced heirship, spousal elective shares, and probate procedure. Faraid shares only take practical effect to the extent a family chooses to follow them voluntarily, or structures a valid will and estate plan under local law to achieve a Faraid-consistent outcome.

This is one of the most important practical points on this page: a Muslim family that wants an estate divided according to Faraid in a country where that is not the default legal outcome generally needs a will and estate plan drafted by a licensed attorney familiar with both the local law and the family's religious intentions. Relying on Faraid shares alone, without a legally valid will under local law, can produce a result that differs from both the religious and the family's intended outcome.

Frequently asked questions

Can a Muslim write a will that overrides Faraid?

The widely taught position is that a Muslim may leave up to one third of the estate through a will (wasiyyah) to people who are not already fixed-share heirs, such as a charity, a friend, or a more distant relative. Leaving a will that attempts to override the fixed shares for the primary heirs themselves is a separate and more contested question; discuss it with a scholar before relying on any specific answer.

Does a daughter really inherit half of what a son inherits?

In the specific scenario where a son and daughter are both residuary heirs together, the son's per-person share is twice the daughter's. This ratio does not apply to every heir pairing; a wife's and husband's shares, for example, follow entirely separate fixed fractions.

What about adopted children, stepchildren, or children born outside marriage?

These situations involve specific, debated rules in Islamic jurisprudence that are outside the scope of this page and its calculator. They require direct guidance from a qualified scholar.

Is this calculator accepted by courts or Islamic authorities?

No. This calculator is an educational tool for understanding how the common fixed shares work. It is not a certified, binding, or officially endorsed computation, and it is not a substitute for a scholar's ruling or an attorney's legal advice for an actual estate.